Surgical adhesions are abnormal scar tissue that can form inside the body as a result of the healing process that follows open or minimally invasive surgical procedures, including abdominal, gynecologic, cardiothoracic, spinal, plastic, vascular, ENT, ophthalmologic, urological, neurological, orthopedic surgery, among others. Briefly, localized areas of injury trigger inflammatory and healing responses that result in healing and scar tissue formation. If scarring results in the formation of fibrous tissue bands or adherence of adjacent anatomical structures that are normally separate, surgical adhesion formation is said to have occurred. Complications from surgical adhesions are a major cause of failed surgical therapy and are a leading cause of bowel obstruction and infertility. Other adhesion-related complications include chronic back or pelvic pain, urethral obstruction and voiding dysfunction. Relieving the post-surgical complications caused by adhesions generally requires another surgery. However, the second surgery is further complicated by adhesions that formed as a result of the previous surgery. In addition, the second surgery can result in further adhesions and a continuing cycle of additional surgical complications. Although a potential complication of any surgical intervention, surgical adhesions are particularly problematic in GI surgery (causing bowel obstruction), gynecological surgery (causing pain and/or infertility), tendon repairs (causing shortening and flexion deformities), joint capsule procedures (causing capsular contractures), and nerve and muscle repair procedures (causing diminished or lost function).
Without wishing to be bound by theory, it is believed that adhesions generally begin to form within the first several days after surgery. Adhesion formation is typically an inflammatory reaction in which various factors are released, increasing vascular permeability and resulting in fibrinogen influx and fibrin deposition. This deposition forms a matrix that can bridge abutting tissues. Fibroblasts accumulate, attach to the matrix, deposit collagen and induce angiogenesis. If this cascade of events can be prevented within the first few days following surgery, then adhesion formation may be inhibited.
Various modes of adhesion prevention have been examined, including (1) reduction of local tissue inflammation, (2) prevention of fibrin deposition and (3) removal of fibrin deposits. For example, inflammation may be reduced by the administration of drugs such as corticosteroids and non-steroidal anti-inflammatory drugs. The removal of fibrin deposits has been investigated using proteolytic and fibrinolytic enzymes.
Fibrin deposition may be prevented through the use of physical barriers, which have the advantage of physically preventing adjacent tissues from contacting each other and thereby reducing the probability that they will scar together. Examples of barrier materials include films such as those formed from oxidized regenerated cellulose (e.g., Interceed™, Gynecare, Ethicon division of Johnson and Johnson, Arlington, Tex., USA), hyaluronate/carboxymethylcellulose (Seprafilm™, Genzyme Corporation, Cambridge, Mass.) and polytetrafluoroethylene (Preclude™, W.L. Gore & Associates, Flagstaff, Ariz., USA), among others.
There are also a number of sprays, solutions, gels, and powers that are intended for use as adhesion barriers including those formed from hyaluronic acid (Sepracoat™, Genzyme Corporation), crosslinked hyaluonan (Sepragel™, Genzyme Corporation), and cross-linked ferric hyaluronate (Intergel™, Gynecare), Ringers lactated solution, a solution of dextran 70 in dextrose (Hyskon™, Cooper Surgical Shelton, Conn., USA), icodextrin solution (Adept™, Innovata plc, Farnham, Surrey, United Kingdom), polyglycan ester in a gelatin matrix (Adcon™, Gliatech Inc., Cleveland, Ohio, USA), sprayable functionalized polyethylene glycol (SprayGel™, Confluent Surgical Inc. Waltham, Mass., USA), a gel composed of polyethylene oxide and carboxymethylcellulose stabilized by calcium chloride (Oxiplex™, FzioMed, Inc., San Luis Obispo, Calif., USA), a synthetic surfactant formulation of dipalmitoylphosphatidycholine and phosphatidyl glycerol (Adsurf™ from Britannia Pharmaceuticals Ltd., United Kingdom), and a sprayable self-polymerizing liquid hydrogel (Adhibit™, Cohesion Technologies, Palo Alto, Calif., USA), among others.
Further information regarding adhesion barrier materials can be found, for example, in S. Rimbach, Adhiesions News $ Views, Issue 8, November 2005, pp. 26-29, U.S. 2005/0208095 to Hunter et al., and U.S. Pat. No. 6,235,796 to Niazi.